Place the water, kombu, and sea salt in a large pot. Bring to a boil and remove the kombu. (Reserve it to use in another dish, such as the next time you cook beans.)

Meanwhile, place the oil in a cast iron skillet and fry the onions. After they are brown, cover the skillet and continue to cook on low until the onion mixture is a thick goo. This may take anywhere from 1 to 2 hours. Give them a stir occasionlly so they don’t stick.

Add the onions to the kombu stock. Return the broth to a simmer.

Season with a generous splash of shoyu.

If you are using mochi, place the mochi in the broth and cover the pot. Cook for 5 minutes, or just until the mochi melts. Serve and enjoy!

* Mochi is a cake made from pounded sweet rice. When you add it to soup, it will melt and give you a topping similar to cheese, but much healtheir! You can find it in the refrigerator section of health food stores. For this recipe, use plain (unflavored) mochi.